Mostly just curious if it's doable http://leagueoflegends.wikia.com/wiki/Braum/Background for reference, I think he would be super fun to play out as.
I like Braum as a character too, even if I'm not too good with him.
But on to the actual advice portion. I think the closest way to get to his defensive style of awesome would be the Phalanx Fighter Fighter Archetype, not only does it let you use a tower shield with a spear(including longspears) but more importantly in terms of flavor, it let's you boost the AC of those around you with it's abilities. Possible PrCs would include Stalwart Defender, but you'd have to choose between its awesome abilities(and d12 HD) and get your improved shield boosting abilities.
If you could make a character strong enough to hold somewhere around a quarter ton(guestimating from an old thread that was trying to do the weight math) as a light load, you could probably make it adamantine.
Ways to boost carrying capacity for that would likely paying 1500 to have Muleback Cords(+8 to strength solely for determining carrying capacity) added to your standard cloak of resistance, and maybe 2000 for a heavyload belt(permanent Ant Haul Effect), combine all that and you should be able to carry around a nigh indestructible shield that will let you shield allies and poros alike.
You could probably get your DM to let you allow the glammered armor effect to let you walk around barechested even though you're wearing armor. Normally it just makes it look like clothing and stuff.
Hope it helps :)